Subscriber telephone instruments have become increasingly sophisticated in features and functions over the past several decades. Simple rotary dial telephones with primitive electromechanical components were obsoleted by push button dial telephones with primitive analog circuit components. The primitive push button dial telephones were obsoleted by sophisticated electronic telephones that use programmed microprocessor technology to implement basic telephone functions and to offer advanced features such as speed dialing, directory dialing, telephone call logging, and additional sophisticated features. This technical progress is shown in the following U.S. Patents:
Lenaerts et al. U.S. Pat. No. 3,920,926 Title: "Telephone data set including visual display means"
Hoff et al. U.S. Pat. No. 3,932,709 TITLE: "ELECTRONIC BUSINESS TELEPHONE"
Warren U.S. Pat. No. 4,011,414 TITLE: "AUTOMATIC DIAL SYSTEM FOR A SUBSCRIBER TELEPHONE"
Mallien U.S. Pat. No. 4,122,304 TITLE: "CONTROL CIRCUITRY FOR A RADIO TELEPHONE"
The Warren and Mallien patents show the implementation of subscriber telephone features using programmed microprocessors.
Parallel with the development of microprocessor based smart telephones, point of sale terminals which incorporate microprocessor based telephone and data terminal features were being developed. Examples of such systems are described in the following U.S. Patents:
Borison et al. U.S. Pat. No. 3,983,090 TITLE: "TERMINAL APPARATUS"
Chang et al. U.S. Pat. Nos. 4,788,420 and 5,019,696 TITLE: "SYSTEM AND METHOD FOR READING . . . "
With cost-performance improvements in in microprocessor and memory systems it eventually became possible to integrate subscriber telephone and data terminal features into a single screen telephone instrument. Such sophisticated screen telephones include alphanumeric keyboards in addition to telephone keypads. They are capable of performing a number of telephone and home terminal functions. Examples of such screen phones are shown in the following U.S. Patents:
Anderson et al, U.S. Pat. No. 4,291,198 TITLE: "GENERAL PURPOSE ELECTRONIC TELEPHONE STATION SET"
U.S. Pat. No. 4,533,791 TITLE: "INPUT/OUTPUT DEVICE ARRANGEMENTS FOR TERMINALS"
U.S. Pat. No. 5,008,927 TITLE: "COMPUTER AND TELEPHONE APPARATUS WITH USER FRIENDLY COMPUTER INTERFACE INTEGRITY FEATURES"
Lawlor et al. U.S. Pat. No. 5,220,501 TITLE: "METHOD AND SYSTEM FOR REMOTE DELIVERY OF RETAIL BANKING SERVICES"
While each of these patents shows the combination of an alphanumeric keyboard and a telephone keypad in a subscriber telephone, none of them provides a truly user friendly, reliable and simple integration of both types of key-in units in a single instrument.